# Two Channel Chemistry and Imaging on the MiSeq i100 Series
**Background**
The MiSeq i100 Series uses two-color chemistry, which allows for rapid imaging of the flow cell using blue and green fluorescent excitation channels at every sequencing cycle. The MiSeq i100 Series is powered by XLEAP-SBS chemistry, a faster, higher quality, and more robust update to Illumina's sequencing by synthesis (SBS) chemistry.
*Chemistry*
In two-channel chemistry, the base calls are assigned by the fluorescent excitation-emission spectra that are designated by that base. The MiSeq i100 Series uses the following designations:
* Clusters with intensity in **green** only: **T**
* Clusters with intensity in **blue** only: **C**
* Clusters with intensity in both channels: **A**
* Clusters with no intensity/dark: **G**
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*CMOS Flow Cell*
The MiSeq i100 Series uses a patterned flow cell with nanowells fabricated onto a CMOS chip.
*Imaging Tiles*
5M: 1 lane x 9 swaths x 2 tiles = total of 18 tiles imaged.
25M: 1 lane x 9 swaths x 10 tiles = total of 90 tiles imaged.
50M: 2 lanes x 9 swaths x 10 tiles = total of 180 tiles imaged.
100M: 4 lanes x 9 swaths x 10 tiles = total of 360 tiles imaged.
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| *For any feedback or questions regarding this article (Illumina Knowledge Article #9348), contact Illumina Technical Support* [*techsupport@illumina.com*](mailto:techsupport@illumina.com?subject=Question%2FFeedback%20Regarding%20Illumina%20Knowledge%20Article%20#000009348%20-%20Instrumentation%20\&body=Dear%20Illumina%20Technical%20Support,%0D%0A%0D%0A)*.* |
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